Troubleshooting
DTC P0112 INTAKE AIR TEMPERATURE CIRCUIT LOW INPUTCIRCUIT DESCRIPTION
DTC Detection Condition:
The intake air temperature sensor is built into the mass air flow meter and senses the intake air temperature.
A thermistor built in the sensor changes the resistance value according to the intake air temperature.
The lower the intake air temperature, the greater the thermistor resistance value, and the higher the intake air temperature, the lower the thermistor resistance value (See fig.1).
The intake air temperature sensor is connected to the ECM. The 5 V power source voltage in the ECM is applied to the intake air temperature sensor from the terminal THA via resistor R.
That is, the resistor R and the intake air temperature sensor are connected in series. When the resistance value of the intake air temperature sensor changes in accordance with changes in the intake air temperature, the potential at terminal THA also changes. Based on this signal, the ECM increases the fuel injection volume to improve driveability during cold engine operation.
If the ECM detects the DTC P0110, P0112 or P0113, it operates the fail-safe function in which the intake air temperature is assumed to be 20 °C (68 °F).
HINT: After confirming DTC P0110, P0112 or P0113 use the hand-held tester or the OBD II scan tool to confirm the intake air temperature from the "DIAGNOSIS/ENHANCED OBD II/DATA LIST/ALL DATA".
Wiring Diagram:
Step 1:
Step 2:
Step 3:
Step 4:
Step 5:
INSPECTION PROCEDURE
HINT:
- If different DTCs that are related to different Systems are output simultaneously while terminal E2 is used as a ground terminal, terminal E2 may be open.
- Read freeze frame data using the hand-held tester or the OBD II scan tool, as freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, it is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich, etc. at the time of the malfunction.
CHECK FOR INTERMITTENT PROBLEMS
hand-held tester only:
By putting the vehicle's ECM in the check mode, 1 trip detection logic is possible instead of 2 trip detection logic and sensitivity to detect open circuits is increased. This makes it easier to detect intermittent problems.
1. Clear the DTC.
2. Set the check mode.
3. Perform a simulation test.
4. Check the connector and terminal.
5. Handle the connector.